Vehicle position detecting apparatus

ABSTRACT

A vehicle position detecting apparatus includes: a position measurement unit that obtains first position information of a first vehicle; an autonomous sensor that obtains relative position information of a second vehicle; a receiver that receives communication data containing second position information of the second vehicle; an identification unit that performs identification on the second vehicle specified based on the relative position information and the second vehicle from which the communication data is sent; a position error calculator that calculates a position error between a position of the second vehicle specified based on the relative position information and that of the second vehicle specified based on the second position information; and a position corrector that performs, based on the position error, a correction on the position of the second vehicle specified based on the second position information, on a condition that the identified second vehicle is no longer detected by the autonomous sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Japanese Patent ApplicationNo. 2015-096382 filed on May 11, 2015, the entire contents of which arehereby incorporated by reference.

BACKGROUND

The technology relates to a vehicle position detecting apparatus thatdetects a position of a vehicle.

A driving support system that utilizes vehicle-to-vehicle communicationmay involve a decrease in accuracy of support, due to an error includedin position information of another vehicle obtained by thecommunication. Another vehicle may be a surrounding vehicle presentaround an own vehicle.

To address the decrease in accuracy of support, a method has beenproposed in which position information of the surrounding vehicle,obtained from a detection performed by an autonomous sensor, is used inaddition to the position information obtained by the communication,without solely relying on the position information obtained by thecommunication. The autonomous sensor may be, for example but not limitedto, a millimeter-wave radar sensor. For example, reference is made toJapanese Unexamined Patent Application Publication (JP-A) Nos.2008-46873 and 2011-221869.

SUMMARY

In general, a proposal on a method that makes it possible to increase adetection accuracy of a position of a vehicle and thereby to improveaccuracy of support has been demanded with respect to a driving supportsystem.

It is desirable to provide a vehicle position detecting apparatus thatmakes it possible to increase a detection accuracy of a position of avehicle.

An aspect of the technology provides a vehicle position detectingapparatus that includes: a position measurement unit that measures aposition of a first vehicle as an own vehicle to obtain first positioninformation as position information of the first vehicle; an autonomoussensor that detects a relative position, relative to the first vehicle,of a second vehicle to obtain relative position information of thesecond vehicle, in which the second vehicle is a vehicle different fromthe first vehicle; a receiver that receives communication data obtainedby the second vehicle and sent from the second vehicle, in which thecommunication data contains second position information as positioninformation of the second vehicle; an identification unit that performsidentification on the second vehicle specified based on the relativeposition information and the second vehicle from which the communicationdata is sent, based on the first position information, the relativeposition information, and the second position information; a positionerror calculator that calculates, for the second vehicle identified bythe identification unit, a difference, as a position error, between aposition of the second vehicle specified based on the relative positioninformation and a position of the second vehicle specified based on thesecond position information; and a position corrector that performs,based on the position error, a correction on the position of the secondvehicle specified based on the second position information, on acondition that the second vehicle identified by the identification unitis no longer detected by the autonomous sensor.

The position corrector may average, on a time axis, the position errorsequentially calculated for the second vehicle identified by theidentification unit, and may perform the correction, based on theaveraged position error.

The position corrector may adjust the position error, based on one of anelapse of time from and a traveling distance of the second vehicle froma time point at which the second vehicle identified by theidentification unit is no longer detected by the autonomous sensor.

A driving support controller may be further included that may perform adriving support control on the first vehicle, based on the position ofthe second vehicle corrected by the position corrector.

The driving support controller may perform the driving support controlthat is based on any of control levels that are different depending on atraveling position of the second vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating an outline of a configuration ofa vehicle controller that includes a vehicle position detectingapparatus according to an implementation.

FIG. 2 illustrates an example of communication data invehicle-to-vehicle communication.

FIG. 3 is a functional block diagram that describes a position detectionof a surrounding vehicle and a driving support control according to theimplementation.

FIG. 4 describes an example of identifying the surrounding vehicles.

FIG. 5 describes an example of information to be recorded uponcalculation of an average position error.

FIG. 6 describes a significance of performing a position correction.

FIG. 7 is a flowchart illustrating a procedure of processes that relateto the calculation and the recording of the average position error.

FIG. 8 is a flowchart illustrating a procedure of processes that relateto the correction of a position of the surrounding vehicle and thedriving support control.

DETAILED DESCRIPTION

In the following, some implementations of the technology are describedin detail with reference to the accompanying drawings.

1. Overall Configuration of Vehicle Controller

FIG. 1 is a block diagram illustrating an outline of a configuration ofa vehicle controller 1 that includes a vehicle position detectingapparatus according to an implementation of the technology. Note thatFIG. 1 primarily illustrates a configuration of a key part, directed tothe implementation of the technology, of the configuration of thevehicle controller 1.

Referring to FIG. 1, the vehicle controller 1 may include animage-capturing unit 2, an image processor 3, a memory 4, a drivingsupport controller 5, a display controller 6, an engine controller 7, atransmission controller 8, a brake controller 9, sensors and operationmembers 10, a display 11, an engine actuator 12, a transmission actuator13, a brake actuator 14, a bus 15, and a vehicle-to-vehicle communicator16, all of which may be provided in an own vehicle.

The image processor 3 may be configured by a microcomputer thatincludes, for example but not limited to, a central processing unit(CPU), a read-only memory (ROM), and a random access memory (RAM). Theimage processor 3 may execute, based on captured image data,predetermined image processes related to recognition of an environmentoutside the own vehicle. The captured image data may be obtained as aresult of capturing, by the image-capturing unit 2, an image in atraveling direction of the own vehicle. The traveling direction may be aforward direction in this implementation without limitation. The imageprocesses performed by the image processor 3 may utilize the memory 4.The memory 4 may be, for example but not limited to, a nonvolatilememory.

The image-capturing unit 2 may include two cameras. Each of the camerasmay include a camera optical system and an imaging device. The imagingdevice may be, for example but not limited to, a charge-coupled device(CCD), a complementary metal oxide semiconductor (CMOS), or any othersuitable device that allows for imaging. Each of the cameras may causean image of an object to be formed on an imaging plane of the imagingdevice by corresponding one of the camera optical systems, and therebyallow an electric signal that corresponds to an amount of received lightto be obtained on a pixel basis.

The cameras may be so disposed as to allow ranging based on a so-calledstereo image capturing method to be performed. The electric signalobtained by each of the cameras may be subjected to an analog-to-digital(A/D) conversion and a predetermined correction. The signal having beensubjected to the A/D conversion and the predetermined correction may besupplied to the image processor 3 as a digital image signal (i.e., thecaptured image data) that indicates a luminance value on a pixel basis.The luminance value may be represented by any of predetermined number ofgradation values.

The image processor 3 may execute various image processes to obtainforward information, and estimate, based on the obtained forwardinformation and any other data, a traveling course of the own vehicle.The various image processes may be based on each of the pieces ofcaptured image data obtained by the stereo image capturing. The forwardinformation may include, for example but not limited to,three-dimensional object data and lane line data which are located aheadof the own vehicle. Further, the image processor 3 may detect apreceding vehicle that travels on the traveling course of the ownvehicle, based on the obtained forward information including thethree-dimensional object data.

In one specific but non-limiting example, the image processor 3 mayperform the following example processes, as the processes that are basedon each of the pieces of captured image data obtained by the stereoimage capturing. First, the image processor 3 may generate distanceinformation. The distance information may be generated based on theprinciple of triangulation that utilizes a shift amount (i.e., aparallax) between corresponding positions in respective captured images,namely, a pair of captured images as the pieces captured image data.Further, the image processor 3 may perform a known grouping process onthe distance information, and may compare the distance informationhaving been subjected to the grouping process with three-dimensionalroad shape data, three-dimensional object data, etc., which are storedin advance. By making the comparison, the image processor 3 may extractdata including, without limitation, the data on lane line, data onsidewall present along a road such as a guardrail and a curb, and thedata on three-dimensional object such as a vehicle. Based on theextracted data including the lane line data and the sidewall data, theimage processor 3 may further estimate the traveling course of the ownvehicle, and extract or detect, as a surrounding vehicle that moves inthe same direction, any three-dimensional object that is present on thetraveling course of the own vehicle (including the driving lane on whichthe own vehicle travels and any driving lane adjacent thereto in a casewhere the road has multiple lanes per side) and moves at a predeterminedspeed in a direction substantially the same as a direction of the ownvehicle. Hereinafter, the surrounding vehicle that moves in the samedirection may be simply referred to as a “same direction surroundingvehicle”. The predetermined speed here may be, for example but notlimited to, 0 (zero) Km/h or greater. When the same directionsurrounding vehicle is detected, the image processor 3 may calculate arelative distance cd, a relative speed ds, a surrounding vehicle speedss, and surrounding vehicle acceleration sac, as vehicle information ofthat same direction surrounding vehicle. The relative distance cd may beequal to a distance between the own vehicle and the same directionsurrounding vehicle. The relative speed ds may be equal to a rate ofchange of the relative distance cd. The surrounding vehicle speed ss maybe defined as the sum of the relative speed ds and an own vehicle speedjs, where the own vehicle speed js may be a traveling speed of the ownvehicle detected by a later-described vehicle speed sensor 10 a. Thesurrounding vehicle acceleration sac may be equal to a differentialvalue of the surrounding vehicle speed ss. The image processor 3 mayrecognize, out of the same direction surrounding vehicles, anysurrounding vehicle that is present on the driving lane on which the ownvehicle travels as the preceding vehicle. The image processor 3 may alsorecognize, out of the same direction surrounding vehicles, anysurrounding vehicle that involves, in particular, the surroundingvehicle speed ss which is equal to or less than a predetermined value(for example but not limited to, 4 Km/h or less) and does not accelerateas a substantially-stopped surrounding vehicle.

For example, the image processor 3 may obtain the foregoing vehicleinformation on the surrounding vehicle for each frame of each of thepieces of captured image data. The image processor 3 may cause thememory 4 to store or hold the obtained vehicle information sequentially.

The foregoing process of detecting the surrounding vehicle (or the samedirection surrounding vehicle) performed by the image processor 3 is, inother words, a process of detecting a relative position, relative to theown vehicle, of any surrounding vehicle present around the own vehicle.The image-capturing unit 2 and the image processor 3 which are providedto perform such a process of detecting the surrounding vehicle mayconstitute a non-limiting example of an “autonomous sensor” thatautonomously detects the relative position of the surrounding vehiclepresent around the own vehicle.

The driving support controller 5 may be configured by a microcomputerthat includes, for example but not limited to, CPU, ROM, and RAM. Thedriving support controller 5 may execute various control processesrelated to driving support, based on a result of the image processesperformed by the image processor 3 and held in the memory 4, and basedon information on detection, operation input, etc., obtained by thesensors and operation members 10. The driving support controller 5 maybe coupled to the display controller 6, the engine controller 7, thetransmission controller 8, and the brake controller 9 through the bus15, and adapted to perform data communication mutually between thosecontrollers each of which may be configured by a microcomputer as well.The driving support controller 5 may instruct any necessary controlleramong the foregoing controllers to execute an operation related to thedriving support.

Specific but non-limiting examples of the driving support may include anadaptive cruise control (ACC) and pre-crash brake control. In the ACC, atarget vehicle speed St and a target inter-vehicle distance Dt may beset based on an operation input performed through a predeterminedoperation member provided among the sensors and operation members 10.The driving support controller 5 may perform, as the ACC, a constantspeed travel control that causes the own vehicle speed js to meet thetarget vehicle speed St when the preceding vehicle is not detected. Whenthe preceding vehicle is detected, the driving support controller 5 mayperform, as the ACC, a follow-up travel control that causes the relativedistance cd between the own vehicle and that preceding vehicle to meetthe target inter-vehicle distance Dt. The follow-up travel control mayinclude a follow-up stop control and a follow-up start control as well.

As the pre-crash brake control, the driving support controller 5 mayperform a predetermined vehicle control when a determination is madethat the own vehicle may possibly collide against a predeterminedobstacle on the condition that the obstacle has been detected. Theobstacle may be, for example but not limited to, a vehicle present aheadof the own vehicle including the preceding vehicle. The predeterminedvehicle control may be, for example but not limited to, providing adriver with an alert or providing a supplemental brake. Thedetermination as to whether the own vehicle may possibly collide againstthe obstacle may be performed based on information on a distance fromthe own vehicle to the obstacle calculated by the image processor 3.

The driving support controller 5 may be coupled to thevehicle-to-vehicle communicator 16. The vehicle-to-vehicle communicator16 may exchange data between the own vehicle and the surrounding vehiclepresent around the own vehicle, by means of a communication system thatcomplies with a predetermined vehicle-to-vehicle communication standard.The vehicle-to-vehicle communication is not limited to directcommunication between the vehicles. The vehicle-to-vehicle communicationmay include communication that involves a relay such as, but not limitedto, a base station.

FIG. 2 illustrates an example of communication data to be exchangedbetween the own vehicle and the surrounding vehicle by thevehicle-to-vehicle communicator 16. The communication data in anillustrated example may contain, without limitation: date and time ofsending the communication data; a vehicle identification (ID) thatuniquely identifies a vehicle from which the communication data is sent;position information on latitude, longitude, and altitude measured bythe vehicle from which the communication data is sent; and variouspieces of information on a vehicle speed, acceleration, and a stop lampof the vehicle from which the communication data is sent. Theinformation on the acceleration may at least contain information onacceleration that acts in a direction parallel to a traveling directionof the vehicle from which the communication data is sent. Theinformation on the stop lamp may be, for example but not limited to,information that indicates on and off of the stop lamp provided on thevehicle from which the communication data is sent.

Referring to FIG. 1, the driving support controller 5 may also perform,as described later in greater detail, a driving support control that isbased on communication data received from the surrounding vehicle by thevehicle-to-vehicle communicator 16.

The sensors and operation members 10 may generically encompass varioussensors and operation members which are provided in the own vehicle.Non-limiting examples of the sensors included as the sensors andoperation members 10 may include: the vehicle speed sensor 10 a thatdetects a speed of the own vehicle as the own vehicle speed js; anengine revolution sensor 10 b that detects the number of revolutions ofan engine; an accelerator position sensor 10 c that detects anaccelerator position from an amount of pressing down on an acceleratorpedal; a GPS sensor 10 d that measures a position that is based onlatitude, longitude, and altitude; a yaw rate sensor 10 e that detects ayaw rate; an accelerometer (G-sensor) 10 f that detects acceleration;and a brake switch 10 g that may be turned on and off in response tooperation and non-operation of the brake pedal.

As used herein, the term “GPS” is not limited to “Global PositioningSystem” currently operated in the United States, and is intended torefer to a global navigation satellite system (GNSS) as a “satellitepositioning system” in general.

The sensors and operation members 10 may also include any otherunillustrated sensor such as, but not limited to: a mass flow sensorthat detects an amount of intake air to be supplied to an engine; athrottle position sensor that detects a position of a throttle valvewhich is inserted in an intake passage and which adjusts an amount ofintake air to be supplied to each cylinder of the engine; a watertemperature sensor that detects a temperature of cooling water whichindicates a temperature of the engine; and an ambient temperature sensorthat detects a temperature outside the vehicle.

Non-limiting examples of the operation members may include: an ignitionswitch that provides instructions on starting and stopping of theengine; an operation member that performs the operation related to theforegoing ACC; a shift lever that provides instructions on a selectionof an automatic shift mode and a manual shift mode and on a shift up anda shift down upon the manual shift mode in an automatic transmission;and a display changeover switch that switches one display information toanother to be displayed on a multi function display (MFD) provided onthe display 11.

The display 11 may generically encompass various meters, the MFD, andany other display device that presents information to a driver. Themeters may be, for example but not limited to, a speed meter and atachometer provided in a meter panel disposed in front of the driver.The MFD may display various pieces of information together or byswitching one information to another. The various pieces of informationmay include, for example but not limited to, information on mileage ofthe own vehicle, information on an ambient temperature, and informationon instantaneous fuel consumption.

The display controller 6 may control a display operation to be performedby the display 11, based on, for example but not limited to, a detectionsignal and information on operation input supplied respectively from apredetermined sensor and an operation member in the sensors andoperation members 10. For example, the display controller 6 may displaypredetermined information on the display 11 as a part of the drivingsupport, based on instructions given from the driving support controller5. The predetermined information may be, for example but not limited to,an alerting message that may be displayed on a predetermined region inthe MFD.

The engine controller 7 may control various actuators that are providedas the engine actuator 12, based on, for example but not limited to, thedetection signal and the information on operation input suppliedrespectively from a predetermined sensor and an operation member in thesensors and operation members 10. The engine actuator 12 may includevarious actuators that are related to an engine drive such as, but notlimited to, a throttle actuator that drives a throttle valve and aninjector that injects a fuel.

For example, the engine controller 7 may perform a start and stopcontrol of the engine in accordance with an operation of the foregoingignition switch. The engine controller 7 may also control, for examplebut not limited to, fuel injection timing, a pulse width directed to thefuel injection, and a throttle position, based on the detection signalsobtained from predetermined sensors such as, but not limited to, theengine revolution sensor 10 b and the accelerator position sensor 10 c.Upon performing the ACC, the engine controller 7 may determine a targetthrottle position from a map, etc., based on instructions given from thedriving support controller 5, and may control the throttle actuator,i.e., controls an output of the engine, based on the determined throttleposition.

The transmission controller 8 may control various actuators that areprovided as the transmission actuator 13, based on, for example but notlimited to, the detection signal and the information on operation inputsupplied respectively from a predetermined sensor and an operationmember in the sensors and operation members 10. The transmissionactuator 13 may include, for example but not limited to, an actuatorthat performs a shift control of the automatic transmission.

For example, the transmission controller 8 may output a shift signal tothe foregoing actuator in accordance with a predetermined shift patternto perform the shift control, when the automatic shift mode has beenselected by the foregoing shift lever. When the manual shift mode hasbeen set, the transmission controller 8 may output a shift signal, whichfollows instructions on the shift up or the shift down given through theshift lever, to the foregoing actuator to perform the shift control.

The brake controller 9 may control various actuators that are providedas the brake actuator 14, based on, for example but not limited to, thedetection signal and the information on operation input suppliedrespectively from a predetermined sensor and an operation member in thesensors and operation members 10. The brake actuator 14 may includevarious actuators that are related to braking such as, but not limitedto, fluid pressure control actuators that control an output fluidpressure to be outputted from a brake booster to a master cylinder and afluid pressure inside a brake fluid pipe.

For example, the brake controller 9 may control, based on fluid pressureinstruction information outputted from the driving support controller 5,the foregoing fluid pressure control actuators to perform braking of theown vehicle. The brake controller 9 may also calculate a slip rate ofany wheel from detection information obtained from a predeterminedsensor such as, but not limited to, an axle rotation speed sensor andthe vehicle speed sensor 10 a. Further, based on the slip rate, thebrake controller 9 may increase or decrease the fluid pressure by any ofthe foregoing fluid pressure control actuators to achieve a so-calledantilock brake system (ABS) control.

[Position Detection of Surrounding Vehicle and Driving Support ControlAccording to Implementation]

FIG. 3 is a functional block diagram that describes a position detectionof the surrounding vehicle and the driving support control according tothe implementation. In FIG. 3, processes to be executed by the drivingsupport controller 5 are divided by function to illustrate the processesin blocks.

Referring to FIG. 3, the driving support controller 5 may include anidentification processor 5 a, a position error calculation processor 5b, a position correction processor 5 c, and a driving support controlprocessor 5 d.

The identification processor 5 a performs identification on thesurrounding vehicle detected by the image processor 3 and thesurrounding vehicle from which the vehicle-to-vehicle communication datais sent, based on information on the position of the own vehiclemeasured by the GPS sensor 10 d, information on the relative position,relative to the own vehicle, of the surrounding vehicle (the samedirection surrounding vehicle) detected by the image processor 3 throughthe foregoing detection process, and position information received fromthe surrounding vehicle by the vehicle-to-vehicle communicator 16.

Hereinafter, the same direction surrounding vehicle detected by theimage processor 3 through the foregoing detection process may bereferred to as a “surrounding vehicle detected by the autonomoussensor”.

FIG. 4 describes an example of identifying surrounding vehicles. In thedrawing, a part having a satin pattern schematically denotes a region inwhich the same direction surrounding vehicle is detectable by the imageprocessor 3.

FIG. 4 illustrates an example in which, as the same directionsurrounding vehicles around the own vehicle, a surrounding vehicle A ispresent on the same driving lane as a driving lane on which the ownvehicle travels, and surrounding vehicles B and C are present on adriving lane adjacent to the driving lane on which the own vehicletravels. The surrounding vehicles A and B each have a vehicle-to-vehiclecommunication function, whereas the surrounding vehicle C has novehicle-to-vehicle communication function.

In this case, the position information obtained by thevehicle-to-vehicle communication is the position information thatbelongs to the surrounding vehicle A and the position information thatbelongs to the surrounding vehicle B, excluding the surrounding vehicleC. Hence, the identification is performed only on the surroundingvehicle A and the surrounding vehicle B.

In the example illustrated in FIG. 4, no interrupting object is presentamong the surrounding vehicles A, B, and C as seen from the own vehicle.Hence, the image processor 3 may possibly detect that all of thesurrounding vehicles A, B, and C are the same direction surroundingvehicle. In this case, the surrounding vehicle C may possibly beidentified as the surrounding vehicle A or the surrounding vehicle Berroneously. In particular, an error may possibly occur in the positioninformation measured by each of the surrounding vehicles A and B,meaning that erroneous identification may possibly be carried out if thereceived pieces of position information themselves are used as areference. More specifically, in this case, such an error in measurementof the position information may result in identification in which thesurrounding vehicle A is identified erroneously as the surroundingvehicle B, or identification in which the surrounding vehicle B isidentified erroneously as the surrounding vehicle C.

In consideration of the error included in the position informationobtained from the surrounding vehicle, the identification processor 5 aperforms identification based on the surrounding vehicle detected by theautonomous sensor, for the surrounding vehicle from which thecommunication data is sent. A specific but non-limiting example of amethod of performing such identification may be a method in which anamount of change of a speed per unit time may be calculated for each ofa surrounding vehicle detected by an autonomous sensor and a surroundingvehicle from which communication data is received, and the surroundingvehicles between which a difference in the amount of change of the speedis within a certain rate are identified as the same vehicle.

The identification that takes into consideration the error included inthe position information received from the surrounding vehicle is notlimited to the foregoing method. Any other method is adoptable for theidentification. For example, identification may be performed on thecondition that a difference between a position based on positioninformation and a position detected by an autonomous sensor falls withina predetermined threshold range, and the threshold is set based on ameasurement error that occurs for each communication vehicle.

The position error calculation processor 5 b calculates, for thesurrounding vehicle identified by the identification processor 5 a, adifference between a position of that surrounding vehicle specifiedbased on the information on the relative position detected by the imageprocessor 3 and a position of the surrounding vehicle specified based onthe position information received by the vehicle-to-vehiclecommunication. The position error calculation processor 5 b calculatesthe difference as a position error ΔP.

In the implementation, the position error ΔP may be determined as avalue that uses a relative position as a reference, not as a value thatuses an absolute position based on latitude and longitude as areference. More specifically, the term “relative position” as usedherein refers to a position on a two-dimensional plane defined by anaxis parallel to a traveling direction of the own vehicle (referred toas a “Z axis” hereinafter) and an axis parallel to a lateral directionof the own vehicle (referred to as an “X axis” hereinafter), where aposition of the own vehicle is the origin.

The position error calculation processor 5 b in the implementation mayfirst convert the position information, received by thevehicle-to-vehicle communication from the surrounding vehicle havingbeen identified by the identification processor 5 a, into the relativeposition. Then, the position error calculation processor 5 b maycalculate, as the position error ΔP, the difference between theconverted relative position and the relative position detected by theimage processor 3 with respect to that surrounding vehicle.

The position error ΔP may also be determined as a value that uses anabsolute position as a reference, by converting the relative position,detected by the image processor 3 for the surrounding vehicle, into theabsolute position.

Further, the position of the surrounding vehicle may be determined basedon a position in three-dimensional space that includes altitude. Thismakes it possible to calculate the position error ΔP asthree-dimensional data that includes the altitude.

The position error calculation processor 5 b may sequentially executethe foregoing process of calculating the position error ΔP, each timethe identification is performed by the identification processor 5 a. Inother words, the position error ΔP may be sequentially calculated on atime axis for the identified surrounding vehicle while that identifiedsurrounding vehicle is detected by the image processor 3.

The position correction processor 5 c performs a correction, on acondition that the surrounding vehicle identified by the identificationprocessor 5 a is no longer detected by the autonomous sensor, on theposition of that surrounding vehicle specified based on the positioninformation received through the vehicle-to-vehicle communication. Theposition correction processor 5 c performs the correction on theposition of that surrounding vehicle, based on the position error ΔPcalculated by the position error calculation processor 5 b.

The position error ΔP may contain, for example but not limited to, thevarious error components as described below:

(1) an error determined by a position at which a GPS antenna is mountedin each vehicle;(2) an error due to characteristics of a GPS receiver;(3) an error due to an insufficient accuracy of GPS measurement;(4) an error in quantization upon transmission through thevehicle-to-vehicle communication; and(5) an error due to insufficient detection accuracy of the autonomoussensor.

The foregoing error component (1) may be attributed to circumstanceswhere, for example but not limited to, the autonomous sensor performs arelative position detection that uses a rear end position of asurrounding vehicle as a reference, whereas the position at which theGPS antenna is mounted is located at a position of the surroundingvehicle other than the rear end. The error component (1) is thus not anerror component that varies from moment to moment while driving but isan error component that is characteristic of that vehicle.

The error component (2) may be an error component attributed to ameasurement logic in the GPS receiver. For example, the error component(2) may be attributed to a determination as to which of the signalsbelonging to respective multiple GPS satellites should be processed withgreater emphasis. The error component (2) may be thus an error componentthat is characteristic of a type of each GPS receiver.

The error components other than the error components (1) and (2) mayvary easily from moment to moment while driving and thus may be sort ofa noise-like error component.

The position error ΔP may not be able to properly reflect an error thatis characteristic of a vehicle, under a situation where any noise-likeerror component other than the error components (1) and (2) is included.

To address this concern, the position correction processor 5 c mayperform averaging of values of the position error ΔP sequentiallycalculated on the time axis to remove any error component other than theerror components (1) and (2). In other words, the position correctionprocessor 5 c may cause only a component to be extracted that indicatesthe error that is characteristic of the vehicle.

In the following, the thus-averaged position error ΔP is referred to asan “average position error aΔP”.

Referring to FIG. 5, a description is given of a method of calculatingthe average position error aΔP with respect to the identifiedsurrounding vehicle. FIG. 5 illustrates an example of information to berecorded into the RAM of the driving support controller 5 upon thecalculation of the average position error aΔP.

First, upon receiving through the vehicle-to-vehicle communication thecommunication data from the surrounding vehicle, the driving supportcontroller 5 may associate the vehicle ID with the position information(denoted as “received position information” in the drawing) bothincluded in the received communication data, and record the associatedvehicle ID and the position information into the RAM. In theimplementation, the position information may be overwritten each timethe position information is received. Upon recording the positioninformation, the received information on the absolute position itselfmay be recorded as the position information, or the absolute positionmay be converted into the relative position and the converted positioninformation may be recorded as the position information.

Following the identification of the surrounding vehicle from which thecommunication data is received and the calculation of the position errorΔP of that surrounding vehicle, the driving support controller 5 mayassociate the calculated position error ΔP with the vehicle ID of thatsurrounding vehicle, and record the associated position error ΔP and thevehicle ID into the RAM. The position error ΔP may be sequentiallycalculated each time the position information is received while thesurrounding vehicle is detected by the autonomous sensor, i.e., whilethe surrounding vehicle is identified. Surrounding vehicles with thevehicle IDs from “V0001” to “Vxxxx” in the drawing are the identifiedsurrounding vehicles following the detection by the autonomous sensor.For each of those identified surrounding vehicles, thesequentially-calculated position errors ΔP are recorded over a pastpredetermined time period.

Note that the surrounding vehicle with the vehicle ID “V0002” is asurrounding vehicle from, which the communication data is received butundetected by the autonomous sensor. For such a surrounding vehicle,only the vehicle ID and the received position information are recorded.

The driving support controller 5, i.e., the position correctionprocessor 5 c, may perform the averaging of the position errors ΔP thusaccumulated in the RAM to calculate the average position error aΔP. Inthis implementation, without limitation, each time a new position errorΔP is calculated, the position errors ΔP, calculated within a certainpast time period from a time point at which the new position error ΔP iscalculated, may be averaged to calculate the average position error aΔPsequentially. The averaging may be performed based on, for example butnot limited to, arithmetic averaging of positions in both the X axisdirection and the Z axis direction. The driving support controller 5,i.e., the position correction processor 5 c, may associate the thussequentially-calculated average position error aΔP with the vehicle ID,and record the associated average position error aΔP and the vehicle IDinto the RAM. In this implementation, without limitation, the averageposition error aΔP may be overwritten each time the average positionerror aΔP is calculated.

Further, in response to the calculation of the average position erroraΔP, the driving support controller 5, i.e., the position correctionprocessor 5 c, may associate information that indicates the recordeddate and time of that calculated average position error aΔP with thevehicle ID, and record the associated information on the recorded dateand time and the vehicle ID into the RAM (denoted as “error-recordeddate and time” in the drawing). In this implementation, withoutlimitation, the information on the error-recorded date and time may alsobe sequentially overwritten.

The position correction processor 5 c may perform the correction of theposition of the surrounding vehicle specified based on the receivedposition information. The position correction processor 5 c may performthe correction, based on the average position error aΔP thus held in theRAM.

Note that the average position error aΔP to be used for the correctionmay possibly involve a decrease in reliability due to an elapse of timefrom a time point at which a target surrounding vehicle is determined asbeing no longer detected. One reason is that characteristics of theposition error that occurs in the position information obtained from thesurrounding vehicle may possibly change in response to a change intraveling environment associated with an elapse of time. The change intraveling environment may include, for example but not limited to, achange in acquisition of a GPS satellite.

To address this concern, the position correction processor 5 c mayadjust a value of the average position error aΔP to be used for thecorrection, based on the elapse of time from the time point at which thetarget surrounding vehicle is no longer detected. In one specific butnon-limiting example, the position correction processor 5 c according tothe implementation may adjust the value of the average position erroraΔP to be used for the correction, based on an elapse of time from therecorded date and time (the error-recorded date and time) of thataverage position error aΔP held in the RAM. The adjustment may beperformed by, for example but not limited to, multiplying the value ofthe average position error aΔP by a coefficient that corresponds to theelapse of time from the error-recorded date and time. The coefficientmay be so determined that a degree of the correction is weakened with anincrease in length of the elapse of time. In this implementation,without limitation, a maximum value of the coefficient may be “1”, andan amount of the adjustment may be “0” depending on the elapse of time.

The driving support control processor 5 d may perform the drivingsupport control on the own vehicle, based on the position of thesurrounding vehicle corrected by the position correction processor 5 c.

In this implementation, without limitation, a support control directedto danger avoidance may be performed as the driving support control. Thedanger avoidance may be directed to a situation where asuddenly-decelerating vehicle is detected ahead of the own vehicle. Inone specific but non-limiting example, the driving support controlprocessor 5 d may determine the presence of the suddenly-deceleratingvehicle, based on the information on acceleration included in thecommunication data received by the vehicle-to-vehicle communication. Asthe driving support control in this case, a support control may beperformed that is based on any of control levels that are differentdepending on whether the suddenly-decelerating vehicle is present on thesame driving lane as a driving lane on which the own vehicle travels.Upon performing the support control, the information on the position ofthe surrounding vehicle corrected by the position correction processor 5c may be used.

When the suddenly-decelerating vehicle is present on the same drivinglane as the driving lane on which the own vehicle travels, the drivingsupport control processor 5 d may alert a driver. In one specific butnon-limiting example, the driving support control processor 5 d maydisplay alerting information for the danger avoidance, including textualinformation such as “ATTENTION: VEHICLE AHEAD DECELERATING SUDDENLY”, onthe MFD of the display 11. When the suddenly-decelerating vehicle ispresent on a driving lane different from the driving lane on which theown vehicle travels, the driving support control processor 5 d mayprovide the driver with information notifying the driver of the presenceof the suddenly-decelerating vehicle at another driving lane. In onespecific but non-limiting example, the driving support control processor5 d may display textual information such as “VEHICLE ON OTHER LANEDECELERATING SUDDENLY”, or any information other than the textualinformation, on the MFD of the display 11.

The foregoing alerting information and the provision of information arenot limited to those presented to the driver in a visual way. Thepresentation of the foregoing alerting information and the provision ofinformation may also be performed in an auditory way.

A description is given now of a significance of performing the positioncorrection in a driving support control such as that described above.For example, in the foregoing situation illustrated in FIG. 4, thesurrounding vehicle A present on the same driving lane as the drivinglane on which the own vehicle travels is detected by the autonomoussensor, making it possible to perform the proper driving support, basedon the information on the relative position detected by the autonomoussensor. However, if the surrounding vehicle C makes a lane change to thedriving lane on which the own vehicle travels as illustrated in FIG. 6from the situation illustrated in FIG. 4, the surrounding vehicle A willbe located at a blind spot of the autonomous sensor, meaning that thedetection has to be rely on the communication data obtained by thevehicle-to-vehicle communication for the position of the surroundingvehicle A. Under such circumstances, handling the position of thesurrounding vehicle A based solely on the communication data maypossibly lead to an erroneous determination as to whether thesurrounding vehicle A is present on the same driving lane as the drivinglane on which the own vehicle travels. This may in turn prevent thedriving support that is based on the appropriate control level frombeing performed when the surrounding vehicle A has decelerated suddenly.In contrast, the implementation that performs the foregoing positioncorrection that reflects the position errors allows for appropriatehandling of the position even when the suddenly-decelerating vehicle,i.e., the surrounding vehicle A, is located at the blind spot, making itpossible to perform the driving support that is based on the appropriatecontrol level.

3. Procedure of Processes

A description is given, with reference to flow charts illustrated inFIGS. 7 and 8, of an example of a procedure of processes to be performedto achieve the position detection of the surrounding vehicle and thedriving support control according to the foregoing implementation.

The processes illustrated in FIGS. 7 and 8 may be executed by the CPU ofthe driving support controller 5 in accordance with programs stored inthe ROM without limitation.

FIG. 7 illustrates a procedure of processes that relate to thecalculation and the recording of the average position error aΔP.

Referring to FIG. 7, in step S101, the driving support controller 5 maywait until the vehicle-to-vehicle communication data is received. Instep S102, upon receiving the vehicle-to-vehicle communication data, thedriving support controller 5 may associate the received positioninformation with the vehicle ID, and record the associated positioninformation and the vehicle ID into the RAM.

In subsequent step S103, the driving support controller 5 may make adetermination as to whether a surrounding vehicle is detected by theautonomous sensor. In other words, the driving support controller 5 maymake a determination as to whether the same direction surroundingvehicle is detected by the image processor 3.

A flow of the processes may return to step S101 (proceeds to “RETURN” inthe drawing) when a determination is made that the surrounding vehicleis not detected. In other words, the driving support controller 5 mayonly associate the received position information with the vehicle ID torecord the associated position information and the vehicle ID into theRAM, when the surrounding vehicle is not detected by the autonomoussensor.

When a determination is made that the surrounding vehicle is detected bythe autonomous sensor, the flow of the processes may proceed to stepS104. In the step S104, the driving support controller 5 may perform theidentification process based on the vehicle detected by the autonomoussensor. In other words, the driving support controller 5 may perform theidentification process based on the same direction surrounding vehicledetected by the image processor 3, for the surrounding vehicle fromwhich the communication data is received. A method of the identificationprocess has been already described above and will not be described indetail to prevent any duplicate description.

In subsequent step S105, the driving support controller 5 may make adetermination as to whether there is any identified surrounding vehicle.In other words, the driving support controller 5 may make adetermination as to, with respect to the surrounding vehicle from whichthe position information is received, whether there is a surroundingvehicle that corresponds in position to the vehicle detected by theautonomous sensor as a result of performing the identification processin the step S104.

A flow of the processes may return to the step S101 when a determinationis made that there is no identified surrounding vehicle.

When a determination is made that there is the identified surroundingvehicle, the flow of the processes may proceed to step S106. In the stepS106, the driving support controller 5 may obtain the information on therelative position of the identified surrounding vehicle. In subsequentstep S107, the driving support controller 5 may calculate the positionerror ΔP of the identified surrounding vehicle. In this implementation,without limitation, the position error ΔP that uses the relativeposition as a reference may be calculated as described above. Hence, thedriving support controller 5 may convert the position information,received from the surrounding vehicle and recorded in the RAM, into theinformation on the relative position, and may then calculate theposition error ΔP.

In step S108, following the calculation of the position error ΔP in thestep S107, the driving support controller 5 may associate the calculatedposition error ΔP with the vehicle ID of the surrounding vehicle andrecord the associated position error ΔP and the vehicle ID into the RAM.

In subsequent step S109, the driving support controller 5 may make adetermination as to whether there is any surrounding vehicle for whichthe position errors ΔP are accumulated for a certain time period. Theflow of the processes may return to the step S101 when a determinationis made that there is no surrounding vehicle for which the positionerrors ΔP are accumulated for the certain time period.

When a determination is made that there is the surrounding vehicle forwhich the position errors ΔP are accumulated for the certain timeperiod, the flow of the processes may proceed to step S110. In the stepS110, the driving support controller 5 may perform the averaging of theposition errors ΔP of the corresponding surrounding vehicle. Insubsequent step S111, the driving support controller 5 may associate theaverage position error aΔP with the vehicle ID of the correspondingsurrounding vehicle, and record the associated average position erroraΔP and the vehicle ID into the RAM.

In subsequent step S112, the driving support controller 5 may record therecorded date and time of the average position error aΔP into the RAM.The flow of the processes may then return to the step S101.

FIG. 8 illustrates a procedure of processes that relate to thecorrection of the position of the surrounding vehicle and the drivingsupport control.

Referring to FIG. 8, in step S201, the driving support controller 5 maywait until the vehicle-to-vehicle communication data is received. Instep S202, upon receiving the vehicle-to-vehicle communication data, thedriving support controller 5 may perform an analysis of thecommunication data. The analysis performed here may be, for example butnot limited to, an analysis that is necessary at least to make adetermination on the presence of the suddenly-decelerating vehicle. Inone specific but non-limiting example, the driving support controller 5may perform, for each surrounding vehicle from which the communicationdata is received, a process of determining a relationship in magnitudebetween a value of the acceleration included in the communication dataand a predetermined threshold.

In subsequent step S203, the driving support controller 5 may make adetermination on the presence of the suddenly-decelerating vehicle. Aflow of the processes may return to the step S201 when a determinationis made that there is no suddenly-decelerating vehicle.

When a determination is made that there is the suddenly-deceleratingvehicle, the flow of the processes may proceed to step S204. In the stepS204, the driving support controller 5 may make a determination as towhether the average position error aΔP of the suddenly-deceleratingvehicle is recorded in the RAM. When a determination is made that theaverage position error aΔP of the suddenly-decelerating vehicle isrecorded in the RAM, the flow of the processes may proceed to step S205.In the step S205, the driving support controller 5 may make adetermination as to whether the elapse of time from the recorded dateand time of that average position error aΔP is within a certain timeperiod. This is equivalent to making a determination as to whether theelapse of time, from the time point at which the surrounding vehicle isno longer detected by the autonomous sensor, is within a certain timeperiod. The surrounding vehicle determined as being no longer detectedhere is the surrounding vehicle for which the average position error aΔPhas been calculated.

When a determination is made that the elapse of time from the recordeddate and time of that average position error aΔP is within the certaintime period, the flow of the processes may proceed to step S206. In thestep S206, the driving support controller 5 may adjust the averageposition error aΔP, based on the elapse of time from the recorded dateand time. In subsequent step S207, the driving support controller 5 mayset the position of the suddenly-decelerating vehicle to the positionthat is specified based on the received position information andcorrected by the average position error aΔP. Note that the drivingsupport control in this implementation may handle the position of thesurrounding vehicle on the basis of the relative position. Hence, thereceived position information may be converted into the information onthe relative position, and the correction performed in the step S207 maythen be performed on the converted position information.

The flow of the processes to be performed by the driving supportcontroller 5 may proceed to step S209 upon execution of the correctionprocess of the step S207.

When the average position error aΔP of the suddenly-decelerating vehicleis not recorded in the RAM in the previous step S204 or when the elapseof time from the recorded date and time is not within the certain timeperiod, the flow of the processes may proceed to step S208. In the stepS208, the driving support controller 5 may set the position of thesuddenly-decelerating vehicle to the position specified based on thereceived position information. In this implementation, withoutlimitation, the driving support controller 5 may set the position of thesuddenly-decelerating vehicle to the converted relative position.Following the setting of the position of the suddenly-deceleratingvehicle, the flow of the processes may proceed to the step S209.

In the step S209, the driving support controller 5 may make adetermination as to whether the suddenly-decelerating vehicle is presenton the same driving lane as the driving lane on which the own vehicletravels. When a determination is made that the suddenly-deceleratingvehicle is present on the same driving lane as the driving lane on whichthe own vehicle travels, the flow of the processes may proceed to stepS210. In the step S210, the driving support controller 5 may execute aprocess of providing a driver with the alert as described above.Following the execution of the alerting process, the flow of theprocesses may return to the step S201.

When a determination is made that the suddenly-decelerating vehicle isnot present on the same driving lane as the driving lane on which theown vehicle travels, the flow of the processes may proceed to step S211.In the step S211, the driving support controller 5 may execute a processof providing the driver with the information as described above.Following the execution of the information provision process, the flowof the processes may return to the step S201.

In the foregoing implementation, described is a non-limiting example inwhich the determination is made, based on the uncorrected positioninformation, as to whether the suddenly-decelerating vehicle is presenton the same driving lane as the driving lane on which the own vehicletravels, and in which the driving support control is executed that isbased on the control level that reflects a result of that determination.These determination and execution may be performed in a case where theaverage position error aΔP of the suddenly-decelerating vehicle is notrecorded, or in a case where the elapse of time from the recorded dateand time is not within the certain time period. For these cases,alternatively, the execution of the alerting process in the step S210 orthe execution of the information provision process in the step S211 maybe performed, without making the determination as to whether thesuddenly-decelerating vehicle is present on the same driving lane as thedriving lane on which the own vehicle travels. Alternatively, a processof any driving support control other than the process in the step S210or the step S211 may be performed.

In the foregoing implementation, described is a non-limiting example inwhich the adjustment of the average position error aΔP to be used forthe correction may be performed based on the elapse of time from thetime point at which the identified surrounding vehicle is no longerdetected by the autonomous sensor. However, the adjustment may beperformed based on a traveling distance (a distance of movement) fromthe time point at which the identified surrounding vehicle is no longerdetected by the autonomous sensor.

Further, in the foregoing implementation, described is a non-limitingexample in which the time point at which the identified surroundingvehicle is no longer detected by the autonomous sensor may be the timepoint at which the average position error aΔP is recorded (i.e., thetime point which the error-recorded date and time indicates). However,the time point at which the identified surrounding vehicle is determinedas being no longer detected may be any time point, as long as that timepoint roughly indicates the time point at which the identifiedsurrounding vehicle is no longer detected by the autonomous sensor. Sucha time point may be, for example but not limited to, a time point atwhich the vehicle-to-vehicle communication data is received.

In the foregoing implementation, described is a non-limiting example inwhich the alerting is performed as the driving control in which thesuddenly-decelerating vehicle is present on the same driving lane as thedriving lane on which the own vehicle travels. Alternatively, any othersupport control directed to the danger avoidance may be performed. Sucha support control may be, for example but not limited to, increasing asensitivity of the pre-crash brake control, including, withoutlimitation, easing conditions for activating the pre-crash brakecontrol.

4. Summary of Implementation

The vehicle position detecting apparatus according to the foregoingimplementation may include a position measurement unit, a receiver, anidentification unit, a position error calculator, and a positioncorrector. The position measurement unit measures a position of an ownvehicle. The autonomous sensor detects a relative position, relative tothe own vehicle, of a surrounding vehicle present around the ownvehicle. The receiver receives communication data that is sent from thesurrounding vehicle and contains position information on a position ofthe surrounding vehicle measured by the surrounding vehicle. Theidentification unit performs identification on the surrounding vehicledetected by the autonomous sensor and the surrounding vehicle from whichthe communication data is sent, based on information on the position ofthe own vehicle measured by the position measurement unit, informationon the relative position detected by the autonomous sensor, and theposition information received by the receiver from the surroundingvehicle. The position error calculator calculates, for the surroundingvehicle identified by the identification unit, a difference, as aposition error, between a position of the surrounding vehicle specifiedbased on the information on the relative position detected by theautonomous sensor and the position of the surrounding vehicle specifiedbased on the position information received by the receiver. The positioncorrector performs, based on the position error calculated by theposition error calculator, a correction on the position of thesurrounding vehicle specified based on the position information receivedby the receiver, on a condition that the surrounding vehicle identifiedby the identification unit is no longer detected by the autonomoussensor.

With this configuration, while the relative position of the surroundingvehicle is detected by the autonomous sensor, the position error on theposition of that surrounding vehicle, specified based on the informationon that relative position by the vehicle-to-vehicle communication, iscalculated. When that surrounding vehicle is no longer detected by theautonomous sensor, the correction on the position of that surroundingvehicle specified by the vehicle-to-vehicle communication is performedbased on the calculated position error.

Hence, the vehicle position detecting apparatus according to theimplementation makes it possible to properly detect the position of thesurrounding vehicle that is located outside a detection range of theautonomous sensor, and thereby to allow a driving support system thatutilizes the vehicle-to-vehicle communication to operate properly.

The position corrector may average, on a time axis, the position errorsequentially calculated for the identified surrounding vehicle, and mayperform the correction, based on the averaged position error.

This makes it possible to remove any noise component, i.e., a componentthat varies easily and frequently, related to the position errorattributed to, for example but not limited to, the insufficient accuracyof the GPS measurement in the surrounding vehicle and the insufficientdetection accuracy of the autonomous sensor in the own vehicle. This inturn makes it possible to extract any characteristic component, i.e., acomponent that less frequently varies, related to the position errorattributed to, for example but not limited to, the position at which theGPS antenna is mounted and characteristics of the GPS receiver in thesurrounding vehicle.

Hence, it is possible to more properly correct the position of thesurrounding vehicle, and thereby to allow the driving support systemthat utilizes the vehicle-to-vehicle communication to operate moreproperly.

The position corrector may adjust the position error used for thecorrection, based on one of an elapse of time from and a travelingdistance from a time point at which the identified surrounding vehicleis no longer detected by the autonomous sensor.

This makes it possible to weaken a degree of the correction inaccordance with a degree of a change in the traveling environment, andthereby to address situations where the position error may vary inresponse to the change, from the time point at which the surroundingvehicle is no longer detected by the autonomous sensor, in the travelingenvironment.

Hence, it is possible to reduce a possibility that the execution of thecorrection turns out to be a cause of the erroneous detection of theposition of the surrounding vehicle, and thereby to allow the drivingsupport system that utilizes the vehicle-to-vehicle communication tooperate properly.

A driving support controller may be further included that may perform adriving support control on the own vehicle, based on the position of thesurrounding vehicle corrected by the position corrector.

This makes it possible to properly correct the position of thesurrounding vehicle that is located outside the detection range of theautonomous sensor, and thereby to allow the driving support system thatutilizes the vehicle-to-vehicle communication to operate properly.

The driving support controller may perform the driving support controlthat is based on any of control levels that are different depending onthe position of the surrounding vehicle.

This makes it possible to properly perform the driving support controlthat is based on the control level that reflects the position of thesurrounding vehicle, e.g., based on whether the surrounding vehicle ispresent on the same driving lane as the driving lane on which the ownvehicle travels.

5. Modification Examples

Although some implementations of the technology have been described inthe foregoing by way of example with reference to the accompanyingdrawings, the technology is by no means limited to the implementationsdescribed above. It should be appreciated that modifications andalterations may be made by persons skilled in the art without departingfrom the scope as defined by the appended claims. The technology isintended to include such modifications and alterations in so far as theyfall within the scope of the appended claims or the equivalents thereof.

For example, in the foregoing implementation, described is anon-limiting example in which a sensor that uses the cameras is given asan example of the autonomous sensor. The autonomous sensor is, however,not limited thereto. In a modification example, any other sensor suchas, but not limited to, a sensor that uses a millimeter-wave radar maybe uses as the autonomous sensor.

1. A vehicle position detecting apparatus, comprising: a position measurement unit that measures a position of a first vehicle as an own vehicle to obtain first position information as position information of the first vehicle; an autonomous sensor that detects a relative position, relative to the first vehicle, of a second vehicle to obtain relative position information of the second vehicle, the second vehicle being a vehicle different from the first vehicle; a receiver that receives communication data obtained by the second vehicle and sent from the second vehicle, the communication data containing second position information as position information of the second vehicle; an identification unit that performs identification on the second vehicle specified based on the relative position information and the second vehicle from which the communication data is sent, based on the first position information, the relative position information, and the second position information; a position error calculator that calculates, for the second vehicle identified by the identification unit, a difference, as a position error, between a position of the second vehicle specified based on the relative position information and a position of the second vehicle specified based on the second position information; and a position corrector that performs, based on the position error, a correction on the position of the second vehicle specified based on the second position information, on a condition that the second vehicle identified by the identification unit is no longer detected by the autonomous sensor.
 2. The vehicle position detecting apparatus according to claim 1, wherein the position corrector averages, on a time axis, the position error sequentially calculated for the second vehicle identified by the identification unit, and performs the correction, based on the averaged position error.
 3. The vehicle position detecting apparatus according to claim 1, wherein the position corrector adjusts the position error, based on one of an elapse of time from and a traveling distance of the second vehicle from a time point at which the second vehicle identified by the identification unit is no longer detected by the autonomous sensor.
 4. The vehicle position detecting apparatus according to claim 2, wherein the position corrector adjusts the position error, based on one of an elapse of time from and a traveling distance of the second vehicle from a time point at which the second vehicle identified by the identification unit is no longer detected by the autonomous sensor.
 5. The vehicle position detecting apparatus according to claim 1, further comprising a driving support controller that performs a driving support control on the first vehicle, based on the position of the second vehicle corrected by the position corrector.
 6. The vehicle position detecting apparatus according to claim 2, further comprising a driving support controller that performs a driving support control on the first vehicle, based on the position of the second vehicle corrected by the position corrector.
 7. The vehicle position detecting apparatus according to claim 3, further comprising a driving support controller that performs a driving support control on the first vehicle, based on the position of the second vehicle corrected by the position corrector.
 8. The vehicle position detecting apparatus according to claim 4, further comprising a driving support controller that performs a driving support control on the first vehicle, based on the position of the second vehicle corrected by the position corrector.
 9. The vehicle position detecting apparatus according to claim 5, wherein the driving support controller performs the driving support control that is based on any of control levels that are different depending on a traveling position of the second vehicle.
 10. The vehicle position detecting apparatus according to claim 6, wherein the driving support controller performs the driving support control that is based on any of control levels that are different depending on a traveling position of the second vehicle.
 11. The vehicle position detecting apparatus according to claim 7, wherein the driving support controller performs the driving support control that is based on any of control levels that are different depending on a traveling position of the second vehicle.
 12. The vehicle position detecting apparatus according to claim 8, wherein the driving support controller performs the driving support control that is based on any of control levels that are different depending on a traveling position of the second vehicle. 